


The Harder Stuff

by alicedragons



Series: Heat Wave [2]
Category: Undertale (Video Game)
Genre: Bottom Slim, Heat Fic, M/M, Mating Cycles/In Heat, Mild Masochism, Painful Sex, Penetration, Rough Sex, Smut, Sub Slim, Top Twist, collaring, dom Twist
Language: English
Status: Completed
Published: 2019-01-29
Updated: 2019-01-29
Packaged: 2019-10-18 20:44:57
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,574
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17588087
Author URL: https://archiveofourown.org/users/alicedragons/pseuds/alicedragons
Summary: It turns out Twist's heat isn't quite over just yet. To his great fortune, his beloved masochist friend is more than willing to satisfy his needs. And his needs call for a little roughness.





	The Harder Stuff

**Author's Note:**

> The second part of the heat fic series! Requested by anonymous on tumblr. They asked for feral dom Twist with sub Slim. Hope I did okay! ^_^  
> This is a follow-on from the previous fic in the series. You don't need to have read the first to understand this one, but it gives a little context. And make sure you've read the tags. This one is pretty intense.

When Slim opened the door, Twist was leaning against the frame. He grinned, winking. “Heya, Pup.” Slim eyed him up and down. His face was flushed, and his hoodie was wrapped around his waist, leaving his arms bare and glistening with sweat. Slim lifted a brow bone.

“you’re still in heat?”

Twist shrugged. “Guess so. Wanna lend a hand?”

Slim frowned, but gestured for him to enter, locking the door behind him. “i thought rus helped you.”

Twist hummed, wandering across the living room. “He did.” He took a handful of cashews from the bowl on the coffee table and shovelled them into his mouth. “Haven’ gone inta heat in a while. Guess this one’s stubborn.” He grimaced, turning his face away. “So, we good fer this?”

Slim nodded slowly. “yeah, we’re good.” He studied Twist, frowning. “how bad is it?”

Twist’s shoulders tensed, and he rolled his neck until it clicked. “Ah, y’know.” He looked at Slim, his face set with weariness. “Yer prob’ly gonna be sore afterwards. That a deal breaker?”

Slim snorted. “is it ever?”

Twist smiled. “Thanks, Puppy.”

Slim nodded and turned towards the kitchen. “you want something to eat before we get started? think i have some leftover…” He sucked in a breath as Twist pressed up behind him, bucking against his coccyx. He was hard through his sweatpants, and it wasn’t just bone.

“Ta be honest,” he murmured, kissing Slim’s neck. “‘m not sure I c’n wait that long.”

“alright,” Slim said quietly, inhaling. “let’s just get more comfortable.” He didn’t wait to ‘port them to the bedroom, a wise choice, he quickly realised, as Twist had him on his back before the world had stopped spinning. He lifted one of Slim’s legs around his waist and grinded against him with a soft growl.

He stopped for just a moment to meet Slim’s eye. “I jus’ wanna make sure we’re clear here. Ya know this ain’t gonna be smooth an’ sweet.”

Slim rolled his eyes. “when have i ever liked it smooth and sweet?”

Twist attacked his neck and Slim’s breath caught. “I could hurt ya,” Twist breathed, voice low. Dangerous.

Slim shuddered, squeezing his legs around Twist’s waist. “i know.”

Twist pulled back, studying him. “Ya have it here?”

Slim nodded at the nightstand. “top drawer.” Twist pulled open the drawer and took out the plain black leather collar. He fastened it securely around Slim’s neck, and magic rippled over Slim as the armour defence kicked in. The defence was high enough to protect his HP from taking any hits, if Twist’s control slipped. Enough outside of heat anyway. In heat, he could only hope.

Twist purred and tugged on the collar to lift Slim’s head, kissing him hard. He shucked Slim’s jacket off his shoulders, then his shirt. His eye-light flitted over Slim’s bones, and gold magic glowed in his mouth. Pushing him back onto the bed, he leaned down and latched onto his sternum with his teeth, sinking them in. Slim moaned, clinging to him while he licked the wound. When he kissed Slim, his tongue tasted coppery with marrow.

Twist removed his own shirt, and Slim was hit with a heavy wave of warmth. Twist’s chest burned against his, and Slim dragged him closer. “come on. show me why you’re here. get those pants off.”

Twist hummed and pulled Slim’s sweatpants off, then his own. He pushed Slim back, then closed a hand around his throat for just a moment, cutting off his air supply. Slim choked on a gasp and magic rushed downward. His cunt throbbed. Twist grinned, his eye-light bright and wild. He hoisted Slim’s legs over his shoulders. “Ready, sweetheart?”

“fuck—yes, come on.” Twist lined himself up, sinking into him in one deep thrust. Slim gasped, crying out in pleasured pain. “hah! fuck, twisted!”

Twist grinned, magic flooding the cracks around his broken socket. He didn’t hesitate a moment, setting a brutal pace hard enough to rock the bed, each thrust punctuated by a carnal grunt. “Ah, ah fuck!” He growled, pressing Slim into the bed. “Fuck yes. Feel so good ‘round me, Puppy. So nice ‘n tight. Oh, _fuck_ yes.”

Slim groaned, his cunt aching. Every thrust knocked the breath out of him. Tremors ran through the armour in his collar, and the wet slap of magic against magic soon became the crack of bone against bone as Twist hit deeper. He groaned and sped up, his thrusts shaking Slim’s whole body.

“Fuck, _fuck._ Oh yes, Slim, fuck, right there, _oh…_ ” He buried his teeth deep into Slim’s collarbone as he came, and Slim cried out, gasping and clutching to him as his own orgasm pulsed through him. Twist slumped onto his chest, catching his breath, before turning Slim over. He bent him over the edge of the bed and entered him from behind, his cock still painfully hard.

Slim buried his face into the mattress and groaned, clutching to the sheets. “oh, fuck twisted. that’s it, keep going. that’s so fucking good.” Finding a good angle, Twist sank in deep.

“Hah, oh—oh fuck, fuck—Pup—Slim—sweetheart, tha’s so good, I— _fuck._ ” He was babbling, words that meant nothing, yet they made Slim’s magic _burn_.

He found Twist’s hand and laced their fingers together, squeezing. “fuck, twisted, you’ve gotta let me help you out with your heats more often.” Twist growled and pressed himself against Slim’s back, pounding into him. “ah—oh, _fuck,_ ” Slim cried. The bed creaked beneath them, and a fraction of the armour in the collar broke.

Clinging to Slim’s hand, Twist thrust in deep and stayed there, rolling his hips until his cock found Slim’s sweet spot. “fuck, i can’t… twisted…” Slim groaned and came hard, his cunt convulsing around Twist’s cock.

Twist growled and pulled out so that just the tip of his cock was still inside Slim. “Ya like that, Puppy?” He pulled on the collar and Slim choked, his skull snapping back. Twist slammed into him again and groaned. “Fuck, ya do, don’t ya? Yer such a good boy. Takin’ me like this. Takin’ care a’ me. _Fuck,_ Slim.” He came again, his cum hot against Slim’s walls.

Panting, he wrapped an arm around Slim’s chest, going still. “How’re ya holdin’ up, sweetheart?” he asked, a note of tenderness slipping into his voice.

“still with you,” Slim breathed. Twist hummed and kissed the back of his neck. “turn me over again, i want to see your face.”

Twist nipped at his neck and turned him around, laying him on his back. Slim wrapped his legs around Twist and pulled him close, their magic dragging together. Twist grinned and kissed him. “Still got a few more a’ those in me. You good?”

Slim touched his face, smiling when Twist nuzzled into his hand. “come on twisted, give it to me.” He gasped when Twist sank into him again.

“With pleasure.”

 

Slim rested his head on Twist’s chest and Twist put an arm around him. “you broke my bed,” Slim remarked. They were lying at an awkward angle, but Slim was too tired to move, and Twist didn’t seem to care. He grinned, winking at Slim.

“I prefer ta think of it as a team effort,” he said, safely detaching the collar from Slim’s neck. Slim felt the brush of a Check, and Twist exhaled, returning the collar to its drawer. He turned back to Slim, nestling his head into the nape of his neck. He stroked a finger down Slim’s inner thigh, which was sticky with cum. With a soft chuckle, he kissed Slim’s jaw and sat up. “Aw, darlin’. Lemme go run a bath fer ya.” Slim pulled him back down.

“no, i want you to stay here.”

Twist sighed, settling back against him. “Alright. Whatever ya need.”

Slim smirked. “when i wake up in the morning, you’re making me pancakes. with maple syrup. and extra whipped cream.” He thought for a moment. “and strawberries.”

Twist chuckled, thumbing his jaw. “Alright, princess. Ya sound like Rus. He wouldn’ lemme leave ‘til I’d done his laundry fer ‘im.” Slim rolled his eye-lights. “Got the ingredients?”

“nope.”

Twist hummed and squeezed his coccyx. “Cheeky. Guess I’m makin’ a shopping trip too. It’s the least I c’n do fer ya.”

Slim looked up. “how are you feeling?”

“Like I could sleep fer a week. Which is a good sign. Don’ think ‘m gonna be fuckin’ anythin’ fer a while.”

Slim studied him with a small frown. “any idea why rus wasn’t enough?”

“Ah...” Twist waved his hand. “He was. He got me through the worst of it. Just a stubborn heat, I guess.”

Slim laughed softly. “so this was just an excuse for a good fuck?”

Twist hugged him to his chest. “Maybe.”

Sighing, Slim closed his eyes. “mind if i join you in your week-long slumber?”

Twist kissed the crown of his skull. “‘Course not, darlin’.”

 

Twist left the following morning—post-pancake cooking (if it could be called that). After waving him off, Slim returned inside and turned on the air conditioning. He collapsed onto the couch, wiping the sweat off his forehead. It wasn’t surprising that Twist had triggered his heat. It had been a long time coming anyway. But since Twist was out of commission for the next week, Slim was going to have to find someone else to help him out. And he had just the person in mind.

**Author's Note:**

> I'm @dragonfics on tumblr if you'd like to visit me. ^_^ (My blog is 18+).


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